New feature: enable grading

[zmartinovic]

Currently you can't grade this activity, but it would be nice to have this feature also. Maybe you could add this in next version?

[hgeorgsch]

This has low priority, as it is not part of our use case locally, and it runs contrary to the main use case, of improvised discussion.

I shall keep it in mind, and see if it can be resolved, though. There is a question of how grading is supposed to work, and how to deal with improvised questions with no well-defined right answer. A well-defined user story would be useful.

1. Where would the user look for a grading report?
2. Who is the user, teacher or student?
3. What does the expected grading report look like?

If somebody else wants to offer a patch, I shall be happy to help and accommodate it.